Optical networks employ a variety of optical components such as optical equalizers. An equalizer is configured to operate on a beam of light signals. Each light signal is associated with different wavelengths. Different light signals often have different intensities. The equalizer provides each of the light signals with the same intensity.
A typical equalizer includes a demultiplexer for separating light signals of different wavelengths and a beam combiner for re-combining the light signals. A plurality of waveguides connect the demultiplexer and the beam combiner. Each waveguide carries a light signals of a different wavelength. Each waveguide includes an optical attenuator for attenuating the light signals traveling along a waveguide. Because each waveguide carries a light signals of a different wavelength, each attenuator is configured to attenuate the intensity of a different light signal.
During operation of the equalizer, a light beam having a plurality of light signals passes through the demultiplexer. The demultiplexer separates the beam into different light signals that are each carried by a waveguide. The attenuators are operated so as to attenuate the intensity the light signals such that each light signals has about the same intensity. The beam combiner re-combines the light signals into a beam. Each of the light signals in the beam has about the same intensity.
The demultiplexer and the beam combiner can each include two star couplers. As a result, the equalizer can include a total of four star couplers. Star couplers are often large and occupy a large portion of the space available on an optical chip. Additionally, the use of four connected star couplers is associated with high levels of optical loss. As a result, there is a need for an equalizer having a reduced size and/or reduced optical loss.